Conventional mattresses provide a uniform firmness along their lengths and widths. Thus, a conventional mattress, such as those of a conventional coil spring construction or foam rubber-like construction, is relatively soft so that the upper torso of a person supported upon the mattress tends to sag downwardly relative to the legs. In addition, excessively high pressure points are created at the shoulder and hip areas. Typically, since the legs are elevated slightly relative to the lower part of the torso, the individual is not properly supported for maximum comfort. For proper support, the body should be substantially level and the upward support pressure applied along the entire length of the body should be as equal as possible.
In order to provide better support for a person lying upon a mattress, attempts have been made to vary the firmness of the mattress at various locations thereof so as to support the individual more comfortably. One varying firmness mattress, which is disclosed in my prior U.S. Pat. No. 4,679,266 issued Jul. 14, 1987, is provided with four zones or regions which are of different firmnesses. In that construction, the mattress is divided longitudinally into a head region, upper torso region, lower torso region, and leg region. These regions are varied in firmness relative to each other. That is, the upper torso region is most firm, the lower torso and head regions are less firm and are generally of about the same firmness, and the leg region is least firm. With that construction, the user's body is held substantially level whether the user is lying upon his back or side and pressure points are relatively equalized.
Other mattresses have been made and are commercially available in which the mattresses have been divided into thirds along their lengths or into other regions that have varying firmnesses. But these have generally not given an adequate or desirable back support or level, comfortable body support as the mattress disclosed in the above patent.
The present invention relates to improving the construction of the mattress disclosed in my prior patent and particularly making it easier and less expensive to provide that type of mattress in different size ranges for different size people. Since the heights and weights of people vary so much, it is not possible to provide a single mattress whose size and varying firmness will provide a comfortable support for all people. Thus, this present invention is concerned with making it feasible to inexpensively provide a number of different size and firmness mattresses, each of which is constructed to be more comfortable to a preselected range of size and weight people.